Specialty Pharmaceuticals: Therapy Class Review: Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, debilitating disease that attacks the central nervous system (CNS). The CNS is made up of the brain, spinal cord, and optic nerves. The resulting effect of MS is a loss of muscle control, vision, balance, and sensation. MS is thought to be an autoimmune disease whereby the body’s immune system, which normally targets and destroys substances foreign to the body such as bacteria, instead attacks normal tissues.1

In patients with MS, the immune system attacks the fatty substance, called the myelin, that surrounds and protects the nerve fibers in the CNS and helps in the transmission of nerve impulses—the myelin is consequently destroyed. As a result, nerve impulses carrying messages from the brain and spinal cord are disrupted or halted. No 2 people have exactly the same experience of MS. The disease course and symptoms look very different from one individual to another. Some individuals experience symptoms for a short period and then are symptom-free for a period of months or even years. Other patients may experience a more steady progression of the disease. Although symptoms can vary, the most common include blurred vision, numbness or tingling in the limbs, and problems with strength and coordination.1

The 4 common types of MS are1:

• Relapsing-remitting

• Secondary-progressive

• Primary-progressive

• Progressive-relapsing

Demographic/Prevalence Data

In the United States today, approximately 400,000 people have MS. Aproximately 200 more individuals are diagnosed every week. Worldwide, MS is thought to affect more than 2.5 million people. MS is more common in women than men (2-3 times), and most individuals are diagnosed between the ages of 20 and 50. MS is one of the most common causes of neurologic disability in young and middle-aged adults.1

Economic Impact

The money spent on treating MS continues to be a budget constraint for health plans. Controlling relapses and also modifying the disease may offer a ray of hope in easing the economic burden. MS pharmacotherapy is expensive and now consumes $1 of every $40 of pharmacy benefits to pay for 82.2 claims per month per 100,000 insured members. A lot of hope has been invested in the newer drugs that are currently in clinical trials. It is hoped that these new drugs will be able to slow down the progression of the disease, decrease relapses, and allow patients to live a longer and a less debilitating life.2,3

Current Market Observations

A significant need exists for an MS treatment with superior efficacy to current therapies and a less invasive and time-consuming route of administration. Currently available disease-modifying agents must be given parenterally, necessitating either daily or weekly injections, depending on the medication. Amid an increasingly competitive first-line therapy market, the availability of an oral disease-modifying agent would represent a significant advance for patients with relapsing MS. Several oral products are in the pipeline—5 of which are in an advanced phase 3 stage of development. Among these oral products, fingolimod has recently drawn attention because it has shown to reduce neurodegeneration and en hance repair of the CNS in preclinical studies. Novartis expects to submit regulatory applications for it by the end of 2009. Another drug that is of interest is BioMS’ dirucotide, formerly MBP8298. This drug, even though it is given intravenously, could dominate the market for those patients who have secondary progressive multiple sclerosis (SPMS). Currently, the only treatment for SPMS is mitoxantrone (Novantrone), which is limited by its cardiotoxic side effects. Cyclophosphamide has been used for SPMS, but it has a poor adverse-effect profile, is teratogenic, is in pregnancy category D, and is contraindicated for breast-feeding women.4

With no other drug in the pipeline specifically seeking an indication for SPMS, MBP8298 has great potential if it demonstrates good efficacy and an acceptable side-effect profile. Eli Lilly and Co was granted exclusive worldwide rights to dirucotide in 2007.